Electrode for a metal halide lamp

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EP 1 056 116 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	14.11.2001 Bulletin 2001/46

(43)	Date of publication A2:
	29.11.2000 Bulletin 2000/48

(21)	Application number: 00111104.6

(22)	Date of filing: 23.05.2000

(51)	International Patent Classification (IPC)⁷: H01J 61/073, H01J 61/82

(84)	Designated Contracting States:
	AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
	Designated Extension States:
	AL LT LV MK RO SI

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Priority:

25.05.1999 JP 14469499

(71)	Applicant: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
	Kadoma-shi, Osaka (JP)

(72)	Inventors:
	Takeda, Kazuo Sakai-shi, Osaka 593-8305 (JP) Nishiura, Yoshiharu Otsu-shi, Shiga 520-0865 (JP) Nakayama, Shiki Takatsuki-shi, Osaka 569-1145 (JP) Yamamoto, Takashi Takatsuki-shi, Osaka 569-1020 (JP)

(74)	Representative: Schwarzensteiner, Marie-Luise et al
	Grape & Schwarzensteiner Patentanwälte Sebastiansplatz 7 80331 München 80331 München (DE)

(54)	Electrode for a metal halide lamp

(57) A metal halide lamp using a ceramic arc tube in which less lamp flickering occurs, the flux maintenance factor during the lifetime is high and the possibility of lamp break-off is low. The metal halide lamp includes an arc tube 1 in which iodide pellet of metal halide is filled, and a pair of electrodes are arranged in the ceramic arc tube so that the electrode coils are facing each other. The following relation is satisfied:0.00056 × W + 0.061 ≦ α ≦ 0.0056 × W + 1.61 where α (in mm) denotes a length of the portion of the electrode bar protruding from the end face of the electrode coil and W (in Watt) denotes the lamp power.

Search report